When it comes to knowing how to properly bleed ABS brakes, a modern car's ABS module can make things more difficult than they used to be. Normally, the ABS portion of the system does not need to be bled unless air somehow got into the system (possibly through an empty or defective master cylinder), you've replaced part of the ABS system, a normal bleed doesn't result in a firm pedal, or you want to flush any old fluid out of the system. To determine which type of ABS system you have and the exact steps required to bleed it, consult your owner's manual.
Some ABS systems never require bleeding because they have no reservoir that contains fluid. If you have one of these systems, once you've bled the brakes as you normally would, your job is done. Other ABS systems have a bleeder screw on the ABS module and can be bled just like a normal brake caliper.